Nipple areolar reconstruction is desired in individuals whom have lost a nipple due to cancer, trauma, or congenital absence. Current options for nipple reconstruction include recreating the appearance of a nipple by a prosthetic silicone nipple that is adhered to the skin of the breast mound, surgical reconstruction with or without tattoo to match natural nipple pigmentation, or a tattoo of a nipple.
Surgical reconstruction may be performed using a composite nipple graft from the contralateral nipple, a local skin flap, skin flaps with autologous graft augmentation, skin flaps with alloplastic augmentation, or skin flaps with allograft augmentation.
Composite nipple grafts use a portion of the contralateral nipple as a tissue graft for the nipple reconstruction. This type of reconstruction requires a contralateral nipple with adequate volume to accommodate a donation to the other side. There is also risk of donor site morbidity, nipple discoloration, and loss of sensation of the donor nipple.
Local skin flaps are most commonly used to recreate the appearance of a nipple. Loss of projection occurs in all nipples created from surgical flaps, due to retraction forces of the underlying tissue and contraction of scar tissue. To address loss of projection, surgical flaps may be augmented with autologous tissue such as cartilage or fat. Autologous tissue donation requires a secondary surgical site with risk of donor site morbidity. Surgical flaps may also be augmented with alloplastic substances such as silicone gel, hyaluronic acid, calcium hydroxylapatite (RADIESSE™), hydroxyapatite and tricalcium phosphate (CERATITE™), and polytetrafluoroethylene (PTFE). A major disadvantage of alloplastic augmentation is risk of infection and or extrusion of the substance.
Xenograft tissue such as extracellular collagen matrix derived from porcine small intestinal mucosa (Cook medical nipple reconstruction cylinder) may also be used to augment surgical flaps. However, this type of material may not be used in individuals with sensitivity to porcine material or with irradiated skin. Acellular dermal allografts have been used to augment surgical flaps. Allograft tissue has a higher rate of incorporation with limited resorption, reducing risk of infection and or extrusion. Maintained structure and biochemistry of the tissue matrix allows for tissue integration into the graft, with native cells repopulating the matrix.
All surgical flap reconstructed nipples will flatten by 50-75% over 2 years. In approximately 10-15% of reconstructions, the nipple will lose all projection. The most common reason for dissatisfaction following nipple-areolar reconstruction is lack of projection, followed by color match, shape, size, texture and position. Only 13% of all patients were totally satisfied with their reconstructed nipple areolar complex. Factors that may negatively affect projection include external pressure on the reconstruction, poor surgical design, thin skin and dermis, and lack of subcutaneous fat.
All current methods of nipple reconstruction only recreate the appearance of a nipple. The nipple is a site of specialized epidermis since it is glabrous, associated with a unique gland (mammary), has distinct patterns of epidermal stratification, and expresses unique differentiation markers that are not present in trunk epidermis. During lactation, the nipple undergoes high mechanical strain as well as prolonged exposure to high moisture and digestive enzymes in saliva. In humans, the nipple has approximately 15-20 lactiferous ducts centrally located that are lined mainly by a two-layered stratified cuboidal epithelium. Tightly packed collagen bundles surround the ducts as well as smooth muscle that is oriented parallel and circular to the ducts. The nipple has deep infolding of the epidermis into an extensive papillary dermis with fine collagen bundles. The human areola has similar invaginations of the epidermis, although less dramatic. The human areola has large sebaceous glands called Montgomery's tubercles that are thought to prevent sore or chapped nipples and secrete pheromone substances that aid in nursing. The human nipple areolar complex is more pigmented than surrounding skin with melanocytes abundant not only in the epidermis, but also in the basal layer of the sebaceous gland and lactiferous ducts. It is thought that the growth factor environment of the nipple areolar complex (NAC) tissue promotes melanocyte survival in areas where they are typically not found.
Despite efforts to recreate cosmetic solutions for NAC tissue replacement, there remains a significant need in the art for human NAC replacements capable of reproducing the complex physiological and morphological characteristics of a human NAC.